"Life is too short to stuff a mushroom," the writer Shirley Conran declared in the 1970s. Now a new generation of Britons is struggling to find time – or the swashbuckling confidence – to stuff or carve a Christmas turkey.

At the height of the spending splurge on festive food, supermarkets are reporting record sales of deboned joints and pre-stuffed meats such as turkey crowns and even packs of pre-prepared vegetables and trimmings to be wolfed down for Christmas lunch.

Retailers say that although two-thirds of families will cook their Christmas feast from scratch, the rest are opting for shortcuts that will save them time and stress in the kitchen. For thousands of households that means stocking up on everything from ready-made roast potatoes to pigs in blankets and stuffing balls.

Tesco has gone even further to warn that an entire generation is now unable to carve a chicken or simple joint of meat, as the rise of fast foods and decline of the Sunday roast have taken their toll.

Strong sales of deboned poultry and joints of meat throughout the year are set to swell further during the main Christmas food sales period, Tesco predicted. Its seasonal range of easy-to-carve meat and poultry is up by 50% this year, with a 1.5kg Tesco Finest turkey joint with cranberry sauce and stuffing costing £21.

For shoppers, the big advantage of choosing crowns over whole birds is that they are easier to carve and quicker and easier to cook. They are not always cheap, although Iceland sells a frozen turkey crown (2.4kg) for £14 – and fresh crowns which have just gone into other supermarkets for Christmas are quickly selling out.

Tesco meat buyer Ashley Chatterton said: "The glorious ritual of the Sunday roast was not being handed down from parents to children, and as a result the art of skillfully carving around the bone has declined. It's a shame, as there's nothing quite like the anticipation of a good roast and letting the smell of those succulent juices oozing out of the meat fill the kitchen as you carve."

The British Retail Consortium has forecast that Britons will spend £19bn on food and drink over the festive season, but many shoppers are favouring convenience over the risk of food waste.

The key delivery slots for online grocery tomorrow and Christmas Eve have all been snapped up, leaving supermarkets expecting two hectic days ahead of them as shoppers stock up with last-minute essentials. Tesco alone is expecting to sell more than 3m packets of sprouts – enough to fill 9,000 bathtubs – more than 2.5m parsnips and more than 8m bags of potatoes.

Despite the return to "cooking from scratch", due to the tough economic conditions and popularity of TV cooking shows, there is plenty of evidence that at Christmas many want some culinary short cuts to allow them to spend more time with their families.

At Sainsbury's, sales of bags of washed and prepared Brussels sprouts are up by 127% compared with the same time last year. Over the same period, pre-ordered food items ranging from large turkey centrepieces – complete with stuffing and ready-made sauces – to luxurious seafood platters have risen by 30%.

Sainsbury's said that, although two-thirds (66%) of Britons would cook Christmas dinner from scratch, a third (31%) would cut corners and try to claw back some time by using prepared items.

Marks & Spencer is reporting record sales of prepared vegetables, with a luxury vegetable selection its bestselling line of Christmas food to order – sales are up by almost 40% on last year. The selection includes red cabbage, roast potatoes and honey-roast parsnips – all ready for the "cook" to put straight into the oven.

Turkey crowns are the second top-selling item on M&S's food-to-order service, while it is still offering what could be the ultimate in laziness – its "idiot-proof turkey", which it launched six years ago. A spokeswoman said: "We were the first people to sell this – it comes ready in a bag and stuffed, and in an oven dish – you don't even have to touch the turkey! It flew off the shelves and we've done one ever since."

Other retailers, including Waitrose and Morrisons, have meanwhile reported a surge in the popularity of whole fish as a Christmas centrepiece.

Harrods meat buyer Scott Winston said: "There is no doubt that 'convenient Christmas' has become incredibly popular. However, the Harrods customer still values a traditional product, choosing whole turkeys, ribs of beef and whole fish over pre-prepared [items]."